Synthetic precipitated calcium carbonate (“PCC”) is currently used as an additive in a wide variety of consumer products, such as dentifrice products, foods and food supplements, plastics and elastomers, cosmetics, and paper. PCC can be cleanly and conveniently produced in a precipitation reaction by reacting aqueous Ca(OH)2 (“milk of lime”) with carbon dioxide with water being generated as a by-product. In products such as food and foodstuffs, calcium carbonate is useful not only because it supplies the body with an essential nutrient (calcium), but also serves as a conditioner to prevent caking in food powders.
In addition to food products, PCC products are also widely used in dentifrices, particularly toothpastes, where they function as both abrasives and fillers. Because of this functional versatility and because PCCs, when compared to other dentifrice abrasives such as silica and dicalcium phosphate, are much less expensive, there is a strong desire among toothpaste and dentifrice formulators to include them in their products by substituting them for more expensive dentifrice ingredients.
However, while PCC has the aforementioned advantages, it can also be somewhat difficult to prepare calcium carbonate material to have the combination of properties that make it suitable for use in dentifrices. It has been previously noted that the dentifrice-relevant properties of a calcium carbonate material are strongly correlated to its morphology and particle size. For example, scalenohedral-shaped calcium carbonate particles tend to have small particle sizes and provide relatively insignificant cleaning effectiveness. On the other hand, large rhombohedral-shaped (sometimes referred to as “cubic”) calcium carbonate particles have increased cleaning and abrasive benefits, but often abrade all too well: their abrasiveness leading to a concern for possible damage to teeth and gums.
Thus, calcium carbonate material must be sufficiently abrasive to effectively clean, but must not be so excessively abrasive that it may damage tooth and soft tissue surfaces. Given the foregoing there is a continuing need for PCC material that improves cleaning performance when included in a dentifrice preparation, while not also being excessively abrasive that it may damage the teeth or gums.